High temperature high frequency magnet wire and method of making

A composite magnet wire, comprising:

• a metal wire, wherein the metal wire is at least one of copper, a copper alloy, silver plated copper, nickel plated copper, nickel cladded copper, aluminum, or copper clad aluminum;
• and
• a coating applied to an outer surface of said wire, said coating comprising a polyimide polymer and a plurality of alumina nano particles dispersed in said polyimide polymer, said alumina nano particles having a surface treatment applied to outer surfaces of said alumina nano particles, said surface treatment comprises a phenyl-silane;
• wherein
• the polyimide polymer comprises poly(biphenyltetracarboxylic dianhydride-co-phenylenediamine);
• the phenyl-silane comprises at least one of trimethoxyphenylsilane, triethoxyphenylsilane, or mixtures thereof;
• the coating comprises about 1% to about 10% by weight of the surface treated alumina nano particles;
• the coating on said outer surface has a thickness of about 25 μm to about 50 μm;
• and
• the alumina nano particles having an average particle size of about 20 nm to about 50 nm;
• said composite magnet wire having a thermal degradation temperature index of at least 300° C. as calculated in accordance with ASTM E1641 or ASTM D2307 (2005).